Light emitting diode (LED) lighting systems are becoming more prevalent as replacements for existing lighting systems. LEDs are an example of solid state lighting and have advantages over traditional lighting solutions such as incandescent and fluorescent lighting because they use less energy, are more durable, operate longer, can be combined in red-blue-green arrays that can be controlled to deliver virtually any color light, and contain no lead or mercury.
In many applications, one or more LED dies (or chips) are mounted within an LED package or on an LED module, which may make up part of a lighting unit, light bulb, or more simply a “lamp,” which may also include one or more power supplies to power the LEDs. Some units include multiple LED modules. A module or strip of a lamp includes a packaging material with metal leads (to the LED dies from outside circuits), a protective housing for the LED dies, a heat sink, or a combination of leads, housing and heat sink.
An LED lamp may be made with a form factor that allows it to replace a standard threaded incandescent bulb, or any of various types of fluorescent lamps. LED fixtures and lamps often include some type of optical elements external to the LED modules themselves. Such optical elements may allow for localized mixing of colors, collimate light, and provide the minimum beam angle possible.
In the case of an LED lamp designed to replace a tubular fixture, such as a standard fluorescent “tube” type bulb, the heat sink for the strip of LEDs inside the envelope of the bulb typically blocks light in one direction. However, if the bulb is positioned so that the heat sink is oriented up, towards the top, inside or back of the fixture and the LEDs face outward or down, such an LED lamp can be a viable replacement for a fluorescent tube.